Backstage: Secret-derived values may be exposed in scaffolder task logs

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS

4.9 · CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:N/A:N

EPSS

• CVE-2026-106499: 0.27% estimated exploitation activity in the next 30 days; percentile 19.22 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

Impact Deployments that configure sensitive scaffolder.defaultEnvironment.secrets and allow an attacker to create or modify Scaffolder templates are affected. A template author could cause secret-derived values used during template iteration to be persisted in task logs, exposing those values to users with access to the resulting task logs. Patches Patched in @backstage/plugin-scaffolder-backend version 4.1.0 Workarounds - Restrict permission to create or update Template entities to fully trusted parties, as recommended by the Backstage threat model. - If that restriction cannot be guaranteed, remove sensitive values from scaffolder.defaultEnvironment.secrets until a patched version is available. No complete workaround is known that preserves both untrusted template authoring and access to sensitive default-environment secrets.

Published by the source

7 Oct 2026, 17:59 UTC

Last modified by the source

7 Oct 2026, 18:15 UTC

Source last checked

26 Oct 2026, 13:07 UTC

1. Revision 3 · amended · 26 Oct 2026

   Amended from ghsa record GHSA-mfvq-x7vr-rgqg

2. Revision 2 · amended · 24 Oct 2026

   Amended from osv record GHSA-mfvq-x7vr-rgqg

3. Revision 1 · created · 23 Oct 2026

   Published from ghsa record GHSA-mfvq-x7vr-rgqg

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# Patch Next advisory brief: CVE-2026-106499

Advisory: Backstage: Secret-derived values may be exposed in scaffolder task logs
IDs: CVE-2026-106499, GHSA-mfvq-x7vr-rgqg
Record: https://patchnext.com/advisories/cve-2026-106499 (revision 3, source checked 26 Oct 2026, 13:07 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Medium (CVSS 4.9)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: @backstage/plugin-scaffolder-backend 4.1.0. A vendor fix does not mean a deployment is fixed.

## Affected components
- npm @backstage/plugin-scaffolder-backend: affected < 4.1.0; fixed in 4.1.0

## Suggested inspection (read-only)
- `npm ls @backstage/plugin-scaffolder-backend --all`: lists every installed copy and version, including transitive ones. Run in the project root after `npm ci`.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on @backstage/plugin-scaffolder-backend.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://github.com/advisories/GHSA-mfvq-x7vr-rgqg (GitHub-reviewed advisory GHSA-mfvq-x7vr-rgqg lists affected ranges: npm @backstage/plugin-scaffolder-backend >=0 <4.1.0)
- Verified: https://osv.dev/vulnerability/GHSA-mfvq-x7vr-rgqg (OSV record GHSA-mfvq-x7vr-rgqg lists affected ranges: npm @backstage/plugin-scaffolder-backend >=0 <4.1.0 (fixed))

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